Next-generation semiconductor memory devices (e.g., a ferroelectric random access memory (FRAM), a magnetic random access memory (MRAM), a phase-change random access memory (PRAM), and so forth) are being developed in view of demands for high performance and low power consumption with respect to semiconductor memory devices. In the semiconductor memory devices, memory elements may be formed of non-volatile and variable resistance materials. For example, the memory element may exhibit an electric resistance, which may be selectively changed depending on a current or voltage applied thereto and may be preserved even when a current or voltage is not supplied.